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Re: "Including" other RDF and RDFS files

From: pat hayes <phayes@ai.uwf.edu>
Date: Sat, 28 Sep 2002 23:04:42 -0500
Message-Id: <p05111b04b9bc2947cf12@[65.217.30.172]>
To: seth@robustai.net
Cc: www-rdf-comments@w3.org

>pat hayes wrote:
>
>>>On Saturday 28 September 2002 04:46, Brian McBride wrote:
>>>
>>>>  At 20:26 09/09/2002 -0700, Graham Wideman wrote:
>>>>
>>>>  [...]
>>>>
>>>>  >Is there, for example, some convention whereby a block of RDF can say
>>>>  >"This block of RDF abides by the RDFS schema to be found here", in the
>>>>  >same fashion that an ordinary XML file can specify a DTD by which it
>>>>  > abides?
>>>>
>>>>  Graham,
>>>>
>>>>  Have a look at isDefinedBy and seeAlso and see if they meet your needs.
>>>
>>>
>>>AFAIK the above properties are mostly for human consumption, although the
>>>first one implies some authority.
>>>
>>>It would be grate if we had a property with consistent meaning, as in "this
>>>resource completes the graph, providing metadata about the subject".
>>
>>
>>The trouble with this is that there is no such thing as 
>>'completing' a graph. The aim of RDF is to provide a notation in 
>>which information from many sources can be combined together, so 
>>the 'closed-world' kind of picture where graphs have boundaries 
>>defined by other graphs really does not fit very well.
>
>Are you saying that document-A does not provide a boundary to the 
>RDF graph which is endoced by document-A?   So do all RDF triples in 
>whatever document written by whomever just form one big graph

In one sense but not another. There are clearly syntactic and 
operational boundaries between graphs. But publishing a graph amounts 
to asserting it, and you can draw conclusions from any assertions you 
can find. I know all sorts of things that I read somewhere or was 
told, and Ive forgotten where they came from; but I still know them 
and still use them in my thinking. I think it is fair to say that all 
the published RDF in the world can be thought of as one huge graph, 
in this sense. (Bnodes complicate this simple picture a bit, but the 
essential point is the same.)

>and we (and RDF MT compliant agents) are to ignore the document boundaries?

Certainly. In fact, they are completely invisible to the RDF 
semantics. I envision RDF processors which scour the web looking for 
content relevant to their goals, plucking it out of other graphs and 
merging it together freely and drawing consequences from it. If such 
an engine simply forgot about the original graph boundaries that 
would not affect the conclusions it came to.

>Hmm .... then there would be no boundary between the triples you 
>will find by dereferencing <http://robustai.net/sailor/paradox.rdf> 
><http://localhost:2187/node.html?at=%3Chttp://robustai.net/sailor/paradox.rdf%3E> 
>and the triples you find from dereferencing 
><http://www.w3.org/1999/02/22-rdf-syntax-ns#Property>

Well, 'dereferencing' here just means accessing according to the 
URL/HTTP protocols, and of course at that level the graphs are 
separate documents. But in terms of their meaning, each graph asserts 
the triples in it, in the very same way that it would if those 
triples were somewhere else. The only things that matter to the 
*content* are the triples that get asserted.

Pat


>  .... wow,  I dont know how to make work, .... I must be missing something. 
>Seth Russell
>http://radio.weblogs.com/0113759/


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Received on Sunday, 29 September 2002 00:04:24 GMT

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